Its not a fiat metric but basic idea that a medium of exchange appreciates in value, be it fiat, basket if groceries or an ounce of gold. 

Bitcoin's primarily goal is to detach the state from the money issuance – as evidenced by the inscription in the genesis block. Privacy, while a very important aspect of it, was never the only thing that mattered. 

Monero folks always leave this side of the coin unmentioned while eagerly accenting how bitcoin is shit and monero where it's at because it's more privacy focused.